refactor(data): replace schema classes with readonly models

src/app/tip/__tests__/tip-screen.helpers.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from "vitest";
 
-import { PaymentPlan } from "@/data/schemas/payment";
+import { PaymentPlan, PaymentPlanSchema } from "@/data/schemas/payment";
 import type { PaymentPlanInput } from "@/data/schemas/payment/payment_plan";
 
 import {
@@ -10,7 +10,7 @@ import {
 } from "../tip-screen.helpers";
 
 function makePlan(input: Partial<PaymentPlanInput>): PaymentPlan {
-  return PaymentPlan.from({
+  return PaymentPlanSchema.parse({
     planId: "coins_100",
     planName: "Coins",
     orderType: "dol",